Developers for electrophotography are a dry developer in which toner components containing materials containing a colorant and a resin binder are used in a dry state, and a liquid developer in which toner components are dispersed in an insulating carrier liquid.
Liquid developers allow the toner particles to form into smaller particles, so that they give excellent image quality, thereby making it suitable for commercial printing applications. In addition, in the recent years, with the increasing demands for speeding up, liquid developers with lowered viscosities are also in demand. In other words, liquid developers in which toner particles are stably dispersed at smaller particle sizes and lower viscosities are in demand.
Further, in order to meet the demands for speeding up, liquid developers in which the toner particles exhibit high electrophoretic property, in other words, having excellent chargeability are demanded.
Patent Publication 1 discloses as liquid developers having excellent positively chargeable chargeability and environmental stability, in which toner particles having an appropriate particle size are dispersed, positively chargeable liquid developers in which toner particles are dispersed in an insulating liquid, wherein a liquid developers are characterized in that the toner particles are constituted by matrix particles having an anionic group on surfaces thereof and a film coating the above-mentioned matrix particles, wherein the film is a laminate of at least a first cation layer having repeating structural units derived from a cationic polymerizable surfactant having a cationic group, a hydrophobic group and a polymerizable group, an anion layer having repeating units derived from an anionic polymerizable surfactant having an anionic group, a hydrophobic group and a polymerizable group, and a second cation layer having repeating structural units derived from the above-mentioned cationic polymerizable surfactant in this order, from the matrix particle side, and wherein the outermost layer of the above-mentioned film is a cation layer having repeating structure units derived from the above-mentioned cationic polymerizable surfactant.
Patent Publication 2 describes that a resin binder for a toner containing an amorphous polyester having a furan ring has excellent low-temperature fusing ability and storage property.
In addition, Patent Publication 3 discloses a resin binder for a toner containing an amorphous polyester having a furan ring obtained by polycondensing raw material monomers containing at least a carboxylic acid component and an alcohol component, wherein the raw material monomers contain one or more members selected from a carboxylic acid or an alcohol having a specified structure having a furan ring, and one or more members selected from a carboxylic acid compound having a furan ring other than the carboxylic acid having a specified structure having a furan ring and an alcohol having a furan ring other than the alcohol having a specified structure having a furan ring, and wherein the resin binder for a toner has excellent low-temperature fusing ability and storage property, and has favorable electric stability under high-temperature, high-humidity conditions.
Patent Publication 1: Japanese Patent Laid-Open No. 2007-121660
Patent Publication 2: Japanese Patent Laid-Open No. 2012-107228
Patent Publication 3: Japanese Patent Laid-Open No. 2013-231911